Canon EOS Rebel T3 18-55mm IS II Lens Kit - Manual (Page 96)

f : Changing the Depth of Field
96
To obtain a correct flash exposure, the flash output will be set
automatically to match the set aperture (autoflash exposure). The
shutter speed will be set automatically between 1/200 sec. - 30 sec. to
suit the scene’s brightness.
In low light, the main subject is exposed with the automatic flash, and
the background is exposed with a slow shutter speed set automatically.
Both the subject and background look properly exposed (automatic
slow-speed flash sync). If you are handholding the camera, keep it
steady to prevent camera shake. Using a tripod is recommended.
If you do not want a slow shutter speed to be used, set [2: Flash sync.
speed in Av mode] to [1: 1/200-1/60 sec. auto] or [2: 1/200 sec.
(fixed)] in [7 Custom Functions (C.Fn)] (p.218).
The aperture opening (diaphragm) changes only at the moment when
the picture is taken. Otherwise, the aperture remains fully open.
Therefore, when you look at the scene through the viewfinder or LCD
monitor, the depth of field will look narrow. With the procedure below,
you can check the depth of field before taking the picture.
1
Enable depth-of-field preview to be used.
Under [7 Custom Functions (C.Fn)], set [8: Assign SET
button] to [5: Depth-of-field preview] (p.222).
For details about Custom Function settings, see page 216.
2
Exit the menu.
Press the <M> button two times to exit the menu.
3
Press < 0>.
X The aperture will be stopped down so you can see the depth of field.
I Using the Built-in Flash
3 Depth of Field PreviewN
While looking at the Live View image (p.122) and holding down the < 0>
button, you can change the aperture and see how the depth of field
changes.
COP
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